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.:-:jV:3Ri;.Tj:0I-! .VIiLET on packaging and storage of DEHYDIUTED VEGL.T/.bLhC 

^ Bui-et,u or A;:r\ cultural Chenl. Lr;/ :- 1 ^^^ -^ 3 RAF' 'f 

V^O.l^S" /C-- ir.'J. Kecearch Acral:: _ y;j p^E.CEIVEX3 

, !>-^par"jnent of AerriciLLCure | 

<Lors \ I * JUL 241943 


ii S. G^irtment of Agricu' :.f 

Fe.cka.ij;':iS i'or dehydrated vegetj;.blejj laust protect the ■ ■ uali ty of the contentis 
uncer ^cvsre conditiOnvS of export shipment and storage. conclitionii yary 
vitliin a vide range, i-jid for that reason tin-plate canr, hermeticallv sealed 
for certain dehydrated vegetabiec or vith rriction tops for others, are widely 
used and preferred. Other containers are included in the tent;-tive :.pecif ications 
for boLh the U. S. ^^rvi^r and the Lend -Lease piji'chases 1,/ but have not b^en used to 
any great extent. Through the issuance on July 21, 19A''^i, of Bulletin SPi^GD /^^'^ 
(uhicago) the Qu;.i.rterir.astor Gene'-ral hac approved the use of a sealed, foil 
paekajre. Use of xh:.b package has been reque:-tod as noter^'als for it boccane 
available i nd -whon the present s ;.,) .-.kf: of cans are exiiausted. 

A/-other information sheet in preparation is for manufacturer:; of protective 
wrappings, packages j, and package machinery. Those who want further information 
on substitutes for tin pla^e shotild %-rrite for that sheei,.. 

Experienced food processors reaiiae that the packing room riust be maintained 
in the best of sanitary conditions. It should be well lighted, well ventilated, 
and screened. The floor should be smooth and free of cracks. It should be easily 
cleaned and earily kep^ free of debris. A concrete floor with a slight slope 
and dr£i.ins foi rsudy flushing is best- Permit no accumulation of dried vegetable 
refuse to remain from shift to shift.- Insects breed readily under dark, moist 
conditions o 

Containers Required 

The number of co)i tamers required daily in a dehydrati-on plant usually is 
not l.^rgea Hot many dehydration plants exceed 50 tons in daily input. The net 
output is about one-tenth of the original weight. While 2-gallon cans are listed 
in specifications, the ^-Z^'-^^-lon size is most common., Table 1 shows the dehy- 
dration ratios and range of net weights per 5 gallons commonly used coinmercially, 
and the number of 5-galion • -ired per day for every 10 tons of ini)ut from 
the field. A 25-percent -r-s. ,^30 has been assumed. 

jj For Uo S. Array specifications write the Commanding General, Chicago Quarter- 
master Depot, 1819 West Pershing Road, Chicago, Illinois, and for Federal 
specifications apply to the Agricultural Marketing Acininistrationj U. S. 
Department of /igriculture, Vashington, D.. G. 



- 2 - 

Table 1 
Data For Esti mating Container Demand 


No. ol' 5 gale Cans 
weight per Drying Ratio, per 10 Tons Raw» 


. 0-'./;i 

5 gallons 

Lbs . 

Raw Preuured to 






3/16'' slices 



- 9 to 1 

170 - 






- 15 to 1 

200 ~ 






- 11 to 1 

100 ~ 






- 11 to 1 

laO - 





' \. ; -. ; 



■- to 1 

190 - 






10 ~ 15 


- 5 to 1 








- L, to 1 

3H.» "- 


No standard pe- can have been established o Table 1 shov/s that the 
greatcot de;:i9.nd for con'^ on the basis of raw input i.o the plant, will come 
from sweetpoTjatces A ': t plant would require 1500 to 2000 ^-gallon can;-, per 
2U hours. Ivhile T.b.i;3 rcprer-entG a considerable volurne it rsquires the handling 
of only 60 to 80 c;-: •. . ;;f Because of this low requir'Sriiint, highly?' 
mechanized packc.giij^i; j-i:-v . ■/ not used in plants where 5-gallon Cr-.n-. ■ .:.-e the 
containers for dehvdr^v.xf,d vegetables c 

:. .ng-Room Equipment 

The scale sho'.ij.d have a 50-pound range at mostj since the grosF will be 
generall;/- not over Z-;) cr 30 pounds,. An attachment for indicating the amount 
over or under is useful and a tare weight should be provided, 

A sorting table or conveyor is frequently required.. This may ^oq used for 
various purposes, such at* removal of off-color oieces; and separation of lumps 
of insufficient!:*" d?.led product. 

A large, flat plyvood funnel is frequently used when tray loads of product 
are dumped into transfer cans. It is preferable to pack directly into shipping 
containers so far as is practicable, thus avoiding chance insect infestation. 
In some cases, closed moisture -equalizing bins provided with chutes vrhich open 
over i,he fiilinK ?;•■•■'•" -"o used. 

Vibrators ar-e oi oen used in packing to produce a higher bulk density. 
Cabbage is pressed '.'i-ch man.1;:. fitted into the round openings of the cans.. 


Cans nay be i jtrairyo ic huve frici-ion .-oldered tops.-, with stud holes, 
or tO;..;. v,aich cfxti be vol''e'- on .-.^chineo Hand or rots ting .fia;rie .soldering 
e^aipnent will be needed ijr the first two types, Seni-aut'5T-r-^,ic cap clinchers 
or seaners vill be required when solder is not used. The be secrued from 
can manufacturers. Secore vsoiding irons with more thun nor:na.l watxaite vince 
-■"■-:■: '/ill ^robatl- ''.-_■■■- ■■ "her meliiing point '■'': h=^ ■■:,''!•••:.- 

The bag-in-box container described in Bulletin cji^QSI uy^ will require a 
..:c-. -sealing r^chine with thev?aostaticaliy controilea, heated javs. Controlled 
press '.ire and crimp ^y,je jav;, usual - 

,: , ealin:-; xhe Cans 

The tentaiivr ; ^-. ; . .. :^ ■,--^J.ic c-^^j. j.'or a hei'neoic sc;^! for cabb„^-^ tu^. 
cs.rroT/5. One definition o:' a herpetic seal is that it will confine g.v.5es or 
vapors without iea/.age for long periods. The absence of leak^^ ;e iv shown by 
'.he maintenance of vacuun ressui'e in cans which are vaca'aia or prco;.ai-e 
^> T::e term 'ner: .oi x'' /uay have diffei--:.ric j^i^rif .; cance:; c^e:;oi''.ing to 
wnether x,hero is pre'it-ure. vacuuift, or lax abi^ience of ei'. vr\e ii 

jperatoi'S of deny . l. boiir in mind when pac.-;in,' fy^^~ cans 

for jirmy. Navy or Leno--^:Ju .u anipnen'^ uhat the produce iaay cross thi .-.oc.:y 
. juntcins. One pi-ss ii.- oOi3 foet; others are 7000 feet, and there : r. consider- 
able country at 50'J0 feet -ion to the east of the Rookie. -filled 
can is sealed aL atnosphe h Su.biection of such a seaiea can filled 

at. sch xevel to an alt' j--. -.' -. i;. equivalent to packinf^; the can at 

2 l/<i pounds per square inch {.gauge) internal pressui'e.. The soluered seams and 
closures must be tight at "his presrure. If leaks occur, due i.o this pressure, 
P'o.rt of the containea gas will escape and on approachinjj; sea level again ^ will 
be replaced with air. If a ioaky can were packed at sea level, shipped over a 
>}00-food pass and returnea to sea level, there v/o'jld result e 1, perceni< in-- 
cre&se in the oxygen contt~-r!t if the can^ 

PaCiCiniZ, in /.ir 

The packing of dehy^'- .potatoes is typical of inethods for all products 
which may be packec In axi . .e product must be protected from moisture ab- 
sorption ct temperatures occasiorvrdly as high as 130^ .F . , or as low as -15'^ F. 
Insects must be excluded, ?;'iction-top cans are used for potatoes. The cover 
is spot-solderec .i:'"ter the can is filled to hold It in place durini^ rough 

Kany strip-cu.t.Lnti .uc,<.:;.Lr'es produce strips the len^rth of the ..uiaoo- c:ome 
machines reduce the length to 3A inch. If the machine iz of the for.'.ier tyj^e, 
the dried strips may be broken to approximately 3/4 inch before packin^> Various 
means for crushing may be utilized. Fines should be screenea oute Of course the 
goal of the operutor is to ..-rovide a product that may be restored to appear- 
ance as well as the t;. .;•..• resh vegetable = Vibratory methoas should be con- 
sidered, because vibratiovi •...•jos no: reduce the i:ti'ip lengths, while crushing 

- U - ACE-185 

does. Generally speaking, any dimension of a strip or slice over 1 inch is 
likely to resxilt in loose packing. Sone slices such as those of sweetpotatoes 
and white potatoes are exceptions. They yield noncurling slices and a relatively 
high weight per gallon of dehydrated product. 

Dehydrated vegetables packed in air may be enclosed in nonrigid containers 
made with a laminated foil as the chief moisture-proof material. The vegetables 
included are both white potatoes and sweetpotatoes, turnips, and beets. The 
following description is abstracted from a detailed bulletin, mentioned earlier, 
issued by the Quartermaster General's office. The package is made up of an 
inner bag of laminated glassine. A second bag of heat-sealing cellophane, 
laminated to met&l foil and kraft paper is outside of the first \>ii-i and packed 
in a 5-gallon carton. Two such cartons are packed in an outer bo:.-: or carton. 
All producers of the dehydrated vegetables mentioned sho\ald obtain r'nformation 
regarding this package if they prepare Army shipments: (1) because i is 
stressed as a substitute for metal cans; and (2) because it is typical ^n con- 
struction of various types of carton liners of high moisture resistance. The 
individual cartons are lined and assembled by the use of a rectangular mandrel 
or frame. 

Packaging in Carbon Dioxide or in Nitrogen 

Absence of air is specified for cabbage and carrots. The purpose is to 
lengthen storage life, since in the presence of air the palatability, vitamin 
content, and color are lost more rapidly than in its absence. The containers 
which may be used are solder-top, rectangular cans or cans provided with a 
machine-sealing, non-soldered top. 

It is recommended that for specification purposes a definite maximum limit 
of 2 percent be set on the oxygen content of sealed containers. The analysis is 
to be made at least 12 hours after filling and sealing. 

There are three methods by which air may be displaced effectively below 
the 2 percent oxygen limit. They are: (1) the carbon dioxide snow or "dry 
ice" method; (2) the vacuum bell method; and (3) the cylinder and meter method. 

Carbon Dioxide "Snow" Equipment 

The carbon dioxide "snow" method is recommended as suitable when shipment 
and storage of the solid carbon dioxide blocks result in less than 50 percent 
loss. It was developed in this form by the Dehydration Committee. Unlike water 
ice, this product changes directly into a gas when heated. Solid carbon dioxide 
is shipped for use regularly from Berkeley, California, to inland points 120 
miles away. It is packed in a quadruple corrugated carton to insulate the 
block, which maintains itself at a temperature of approximately minus 70° F. 
A 10-inch cube weighs 55 pounds. A top-opening bin should hold 3 cubic feet 
for every 10 tons of plant capacity. Losses per day are 10 percent during 
shipment and 6 percent per day in storage. 

A storage bin should probably hold enough solid carbon dioxide for three 
days' operations. Let us consider a cabbage dehydrater with a daily capacity 


- 5 - 


of iO ton_- la.yj.'^ ^ . jj.i .;.v. :.^w^v^. By ref-rfcrice x.o Table i, iz is setji; ■.•^.... u iJi 
average of 250 i; -gallon can3 vill be the daily o;jitput, or 750 cans in } o.ayso 
one-quarter pourid of solid r-r^rbon dioxide is used per can, Khich caaounts to 

ISS pounds net in 3 days 
loss per day, r-squiring 
pounds. For Ig; t ovo 
be cillcwed, ■T:\ ' ' 
Since one cubic 
of 3 cubic f 

- f'.vei'age storage time -will be 2 days at 6 percent 
:eipt of 112 percent of 138 pounds;; i.e., of 210 
of "dry ice", space for 50 pounds additionial iriay 
total to be stored at ciny time to 26C pounds, 
' veighs 95 pounds, the bin shouj.d have a capacity 

metal or ply 
procurable, oi 
insuij.ting mate^ ... 
tar paper is piaceu c 
in the insuiati:- 
duck siLnce a hi;. 
because of effort . 

;v,'ood for the frarr;ev;ork of such stort-ge bine-, and 
Use a 6-ineh layer of cork slab insulation, if 
:/., or their equivalent in redwood fiber or other 
;Ood fiber or other flocculent 'material in used, 
' outside of the insalai,ion to prevent ice formation 
/-i-j use a light, 4--inch- thick kapok pc_ .: covered vdth 
. poised cover is frequently left open much of the time 
:.o raise and close it. 

A coffee grin. .-e naeded to break the solid carton dioxide into a 
coarse snow- like fonn 'lallow box to catch the "snow" and a scoop holding 

one-fourtti ..'ound of r.hc 

naterial will be required. Gloves shoulo be v/orn 

"DO prev'-nt injury to the h'^K-^. 
Vith on. 

have a l/l6-inch hoi ■-: :aTiched in tni T.op or lid 

to p2rj;u.t j-'a. ir^ The hole is .... i-^uated in r. .:ii ht ce- 

pre:\ is;i to ;> A drilled hoi uisati. fac .; <i. o of 

the untinned iroa en uio ;>;.das of the hole. 

In oraer to prov:. 
water ?. shallow trougi 
this trough should be 
ing water is passed tr 
The trough should be .: 
A second trough or co: 
length should be such 
capped. A hand-solderi 
trough o 

'c.e which will keep the bottoi:is freely exposed to 
Me wider than the cans is required. ...':; e bottom of 
■■':d with two strips about 1 inch high, c^lowly flow- 
;iif7 trough at a maintained depth of 4- to 6 inches. 
. "..iitween the packing station e.nd the capping machiae. 

■iithout wfiter, receives the capped cans^ Its 
jans will stand in it 10 to 15 minutes after being 
ng station is located at the discharge end of zhe second 

Solid carbon dioxide is available throughout the country c There are two or 
more large chains of distributors. One chain ha^- seven plants or warehouses on 
the Vest Coa^t alone. 

Carbon Dioxide "Snow" Method 

The inethou ....... s L;u-.i,f;- c.nd effective. A little carbon dioxide "snoW ir pre- 

pai'ed by grinding and sifting through a sieve having ten meshes per linear inch. 
O/ie-fourth pound is scooped up in a measure and poured into an empty, tared 
5-gallon can on the scales. The. accuracy of the scooped weight is checked so 
that the correct net weight of vegetables will be assured.. The ground mt-.terial 
is shaken quite evenly over the bottom of the can. The operator then weighs in 
the cabbage or carrots and sets the lid loosely but feccurateiy on the opening 
and the can is placed in the water trough. 

" c 

. .rbon di---. 

'.ne gas gt. 

-lines t.he vo^'ti;;^ -■ 

. pushes the air u 

i-ooed until most o 

of the procesG th- 

L not 

thi-o-: ■■■ 


-pj-xl. l.Tiiie I.- 
:as presi'.ure 





in the ■'Jo. 
Without ^. 

:.ion c 

'•Jo. 1. 

too ejv.r 
should . 
10-iuesh, u li 
repcatc"! ■ i 
cap .: 
in th- ; . 

. frost-nipped heir,' 
:''rom the raethoc 
carbon dioxioe. 
/ided in the firat 
va-:,ho6, cabbage 
ning 6.8 to 1 
:: 3-eightj 
percenL ^.-.wgcsri .. 



";ie Uf.ied 

..cuum-Beil Method 

it vith - ^- 
method requi.r 
is a flat pla- 
is rriachin.^ • 
by a h^. 
air undex- 
Kent depeh^ 
plate, goi 
the pijin^ 
pumps a: 
an inch o;. 
be tc 
Many reci..^' 
the lir' 

J oi' reinovinti air -gallon can.'. :;placing 

;en may be termed ■...-■ .. .uurri-bell me....:. . The 
...'ir to that of a vacuum canning operation. There 
one or more cans . The upper sui'f £ ce of the plate 
Cans cire placed on the ^-late and are covered 
.ith a coianterpo3 se. For the evacuation of the 
.£ provided/ The e.f.iect.'LvenBc:.s o ecu:lp- 

...wss of the joint ' •^.' -'een the bell ..... ,;ie 

air inward, ana c 

.d the air in the can . 

■ .. . o.fpr-y. The lattei- ...... .... . 

- ;,htly fitting be.Ll . to vi 
of absolute vacu-jjn. 
'.ent of oxyj^en, hovevc. . ^ . 
ibis st&ged, thUv': incte^ri-ir' 
■yy-yH^^n content in the corit.' 
'.?. ■ ■' "o is so adjusted th- 
to cause it to bu.I 
-ilieving the vacuuin. 

■Jer-iree of vacuum to which 

Oder. Some 
. ., ..... i.nce, when 

,irter of 

puTpfj may 
-'^ed cans. 

,:-ii'v;e in 
r-i be 

- 7 - ACE-185 

Tb.« ra.cM'xnt.zing and gassing proci-.iurc , i-rre carried on as follows: The 
can is filled with a weighed amount of dehydrHted vegetables, and a cover- 
placed on ito The cover is held above the can by indents tioni- in the periphery. 
The resultant space between the can nnd cover allows a free flow of air out of 
the can and of inert gas into it. The filled can with cover is next placed 
under the vacuujri beil and the bell ih lowered. A vacuum of at least 29 inches 
is now dra-iVTi on the bell and this V'^omm is immediately released with nitrogen 
or carbon dioxide. To be certain that the vacuuin is relieved, a positive 
pressure of 1 to Z pounds per square inch is built up in the be.lic Tlie bell 
is now opened and the can is rejaoveci and henrietioaliy sealed iinm'";diateiy, 

j^]j9. Cylind er and Meter Method 

The Hiost common method of removing air has been by the use of gas run from 
a cylinder through a reducing valve, a rubber tiibs, and a metal pu. -o-e tube 
thrui^t to the- bo"v/t-om of the carj. The ajaount of gas is controlled bv -^,he 
pressure settlnj;; of the reducing vaive and the duration of flow. The jetting 
has usually boon based on the ti^^e required to extinguish a flame at the mouth 
of the can, V,r.i.i'-3 this has soi-.etinies resuJ-ted i:.i analyses below 2 percent 
oxj'"gen^ the tirna is not accurately measured so that analyses of canj:; treated 
in this way hrwa been fo".md to vary several-fold in oxygen content. 

The Dehydration Coirmittee has foun.d that tiie introduction of an iron-case 
di-y gas Meter bet/ween the cylinder and purge tube wan of great as.sistance. 
The stock meter used was squipped witli one of the dials showing 1 cubic foot 
per revolution. 

To purge a canj the gauge is set at 3- pounds par square inch;, the puicge 
tube is thrust to the bottoi?. of the can^ the lid is slid over the opening as far 
as possible, and 2 cubic feet of gas i:- allowed to pass The tube is removed, 
the lid ly- set in places anci the cap is clinched or i-.eaiaod tight.. V&.en carbon 
dioxide is useds 1:5 to 1.6 percent oxygen will be ettained in the closed can, 
V^ith nitrogen, resulth- may be over 2 percent. 

Co ntrol of Insect Ij^gjjtation 

Paragraph C~l-b, Tentative Federal Specifications for Dehydrated ,'>weetpotatoes, 
June, 19V-.;, reads as follows? "If there is evidence of insect infewtution in the 
packaging room or the package, it shall be reri aired that the product ana the 
pacKcges be heated to 135^ ?^ iraiiediately before packaging «" Gas packing of carrots 
and cabbage is specified , This results in an additional safeguard against insect 
infestationj since it has been established that an oxygen content of 3eSv^. then 
2 percent destroys inr-f.ct life in all stages of development c 


Labeling is described by Army, Navy,, or Lend-Leass contracts. Current tenta- 
tive U. So Army and Federal Specifications require, unlesr. otherwise specified, 
that each container shall be marked with the following; 

Nam.e and type of product, the net weight in pounds, the month and year of 


dehydration, ncuae of packer, ^oc<=...xon of proce.-.-£inf-, pif.nt. o.u<... : i-e^-ia xo 
directions for rehydration. 


Piicking i'i define", -u r.'Oth Tentative U.. Co Arm.) -"^na rc-ceic-.I. opecifications £^^. 
Veatei'proof solid fiber j and nailed or wire-bound wood boxes c.rfc the types 
specified for export shiiffJients •.■ The Agricii].tural Marketing Adjuinistration has 
U£ed the paine ;-pecifications in connection vith Tentat"-- "nderai opecifications, 

M£.rkj.n^\- t he^ Shippinjg^ CcViitai ners 

Marking of shipping containers noririsllj'- consists cf; 

N&ine and type of product^ the net weigh i: oi the produc-i;., the gross '-/eight of 
and volume occupied by the container, the date of packs.ging, and the name of 
the contractor. 

It is important for the operator to stencil finished boxes daill.y» The 
stencil shows the date of packing. In case Inspection or analysis of the product 
reveals too high a jnoisture content, for example, the niuaber of cans of product 
subject to question will be less than would be the case if ceveral days' product 
had been grouped together . 

S oo rage at the peh.yda'atui' 

Cases of dehydrated vegetables should be stored under cover. They should 
be away ftdm the roof, or i^feparated from it, by an air L:pace t^o ■ ' heat from 
the roof. 

Two 5-g^illon cans occupy 1.75 cu. ft, v;hen 'ooxeci or 3/o cu« ft. per one 
hundred 5-gallon cans. A 50 -ton plant operating on v/hite potato strips woiild 
pack 10,000 to 14.>00G 5-gallon cans in 7 days. These cans, craved, will occupy 
9,000 to 12,000 cu- ft. This is without an allowance for aisles. 

Dehydrated vegetables should be protected from hea.T/ so far as possible. 
They are ioiown to keep for long periods when cold, and to spoil rapidly if they 
are maintained hot. 

Measurements have been resde on moisture content in reiax-ion to storage 
life. Clearly, the moisture content must be reduced below the point where molds 
■will geiTTiinate and grow. Ex[ieriments s.t 90^ T>\ have deir.onstrated that the life 
of cabbage, determined by retention of vitamin C, is increased 50 percent for 

2/ See War Department QMG Jr'orja #304., Revised. This may be procured by request 

from Chicago Quartermasiier Depot, 1819 West Pershing Road, Chicago; California 

Quartermaster Depc'- '--th and Cla.y Streets, Oaicland, California, or other 
Depots . 

- 9 - ACE-1B5 

each 1 percent decrease in the moistiire content. This relation held over the 
range of 12 to 3 percent moisture. Cimilar relations ha-*-e been noted between 
moisture content and palatability of carrots. 

When a processor turns out a product that is regularly 1 percent below 
specification limits for moisture, he may rest assured that by so doing he is 
lengthening the storage life of his product by a substantial amount. 

For further detailed information address: 

The Dehydration Committee 

Bureau of Agricultural Chemistry and Engineeging 

U. S. Department of Agriculture 

Washington, D. C. 


The Dehydration Committee 

Western Regional Research Laboratory 

800 Buchanan Street 

Albany, California